A basic system to reduce the sonic boom created by supersonic aircraft was disclosed in my U.S. Pat. No. 3,314,629 issued Apr. 18, 1967, providing a converging/diverging nozzle emitting a supersonic jet of fluid aft below the undersurface of the supersonic wing. Thereafter a series of applications was filed employing the underwing energized jet of fluid apart from the wing to recover the energy normally wasted in the shock wave system into useful work by transforming the compression into vorticity. The initial U.S. Pat. of this series was No. 3,904,151, issued Sept. 9, 1975, disclosing an aircraft wing system comprising an underwing manifold/nozzle assembly extending essentially the entire span of the wing and shaping the nozzle to emit this jet of fluid aft as a sheet in an underexpanded manner, with a pressure greater than atmospheric. The opposing perturbation velocities on the interface between the underwing compressing air stream and the energized layer below generate negative (counterclockwise) vorticity, which in a supersonic flow provides an upwash downstream, increasing the pressure on the undersurface enabling the wing to operate at a lesser angle with reduced drag. My subsequent improvement U.S. Pat. No. 4,008,866, issued Feb. 22, 1977, specified the forward portion of the wing undersurface as concave, concentrating most of the compression in a short interaction region near the leading edge, corresponding to the short expansion region of the underexpanded jet. This structure locates the energy transformation mechanism under the forward part of the wing, leaving the aft part of the wing available for energy recovery. My latest improvement application No. 747,505 filed Dec. 6, 1976, now U.S. Pat. No. 4,168,044 accordingly reflects the aft portion of the wing upward so as to benefit from the downstream upwash vortex field, achieving the pressure required for lift on the underside of this aft wing portion at a lesser angle with reduced drag. This streamwise series of functions specifies the wing undersurface as concave, convex, and concave sequentially in the flow direction, thus corresponding to the upper element of a planar supersonic nozzle. The jet manifold and its continuing vortex assembly below comprise the lower surface of this nozzle, acting as a pressure shield within the wing chord and a vortex flap aft of the wing trailing edge.
The underwing jet sheet will have an inertia or resistance to downward deflection in proportion to the square of its velocity. A jet velocity in excess of the flight velocity is required for thrust, but the magnitude of this excess is limited by efficiency considerations, which will vary in differing aircraft applications. Thus in some installations where a large excess jet velocity is provided, the jet will have sufficient stiffness to remain essentially horizontal, and all of its energy can be provided in the form of velocity, which will generate the required excess of vorticity on the upper interface within the wing chord length. In cases where a large excess jet velocity is not provided, the stiffness may still be sufficient because of restrictions on pressure transmission through the rotating vortex structure. Nevertheless, cases may arise where the stiffness is insufficient for the jet to remain horizontal and instead it would be deflected downward with the underwing gap flow. In such a case the velocity retardation above and below the jet would be the same, and the vorticities in the upper and lower interface layers would be of equal magnitude and opposite sign, thus failing to provide the net vorticity reaction to the flow downturn. In such cases further measures may be required to ensure generation of the required reactive vorticity to obviate the dissipative shock wave system.